I can confirm that I too see this problem way more than I would like to. I don't make use of DXDIAG windows, just straight up IS1-5 client windows, all on one monitor and use window swapping (wheel switcher enabled with the 'c' key).

Too often, after logging in I'll go to switch characters and it will be messed up. Going from IS1 to IS5 instead of IS2, plus many more different scenarios of improper switching.

This is a problem I had when I picked up boxing again last year. CPU changes does nothing, extending client launch time does nothing. I can even launch clients by a 'per slot basis' and after all 5 are loaded this way the order will still be wrong switching switching screens.

Very, very frustrating! The only fix I have found (which is mostly luck) is to test switching clients after everything is loaded in. If it worked that time I can play, if not I'll close down and reload the clients.

Or, not tested thoroughly enough as it might just be coincidence, but it seems a couple of times when I deleted the config.wtf files for the individual characters and then tried again everything booted up just fine.

Would love to find a solution to this problem!